The invention relates to a method of analyzing gaseous media by means of microwave absorption, particularly for the determination of gas concentrations, wherein a microwave is generated at least one frequency. The invention also relates to an apparatus for analyzing gaseous media by means of the absorption of microwaves, particularly for a determination of concentrations, primarily for implementing the method and comprising at least one microwave transmitter, at least one measuring cell, at least one reference cell, at least one detector, at least one waveguide "magic" tee, amplifying and display devices for the measurement signal as well as a control device for the microwave transmitter.
It is known to analyze gaseous media, possibly also after conversion of a solid or a liquid into the gaseous state, by absorption of microwaves within certain characteristic frequency ranges by the excitation of rotational transitions in molecules of the media to be examined. If necessary to reduce the line width, the examination may take place in the low pressure range. The absorption of microwave energy by the gaseous component of interest is detected when the absorption upsets the balance of energy arriving at the waveguide "magic" tee via the measuring and reference cells. Such a process is highly selective, in principle, but does not require prior modifications, such as ionization or chemical reactions, of the substances to be examined.
In the past, examination of the concentration of trace amounts of a particular component of a gaseous mixture, directly by the absorption of microwave energy, has not been practiced due to insensitivity and non-specificity of the methods employed.
Nuclear magnetic resonance and electron paramagnetic resonance methods, as opposed to direct microwave absorption methods have demonstrated useful degrees of sensitivity and specificity, but have the disadvantage of complexity, cost, size, difficulty of operation and maintenance and lack of reliability. These negative attributes are evidenced by the absence of commercially available gas analyzers based on microwave methods.